When NOT to use short-term mechanical circulatory support

Central MessageThe use of short-term mechanical circulatory support has emerged as an increasingly popular therapy for a wide variety of cardiac pathologies. While the alternative to providing support is usually imminent death, this should not force clinicians into providing therapy if the outcome is deemed to be futile.See Commentaries on pages 111 and 112. The use of short-term mechanical circulatory support has emerged as an increasingly popular therapy for a wide variety of cardiac pathologies. While the alternative to providing support is usually imminent death, this should not force clinicians into providing therapy if the outcome is deemed to be futile. See Commentaries on pages 111 and 112. The use of short-term mechanical circulatory support (MCS) is increasingly being offered to patients with acute cardiogenic shock.1Rao V. Resurgence of extracorporeal support for the primary management of cardiogenic shock.J Thorac Cardiovasc Surg. 2015; 150: 341-342Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar The results of therapy have been improving consistently, with survival to hospital discharge exceeding 60% for selected cohorts.2Takayama H. Truby L. Koekort M. Uriel N. Colombo P. Mancini D.M. et al.Clinical outcome of mechanical circulatory support for refractory cardiogenic shock in the current era.J Heart Lung Transplant. 2013; 32: 106-111Abstract Full Text Full Text PDF PubMed Scopus (125) Google Scholar,3Thiagarajan R.R. Barbaro R.P. Rycus P.T. Mcmullan D.M. Conrad S.A. Fortenberry J.D. et al.Extracorporeal life support organizing registry international report 2016.ASAIO J. 2017; 63: 60-67Crossref PubMed Scopus (350) Google Scholar One-year survival after hospital discharge is also encouraging, suggesting that those patients who survive short-term MCS have reasonable mid-term outcomes.4Cheng Y.T. Garan A.R. Sanchez J. Kurlansky P. Ando M. Cevasco M. et al.Midterm outcomes of bridge to recovery patients after short-term mechanical circulatory support.Ann Thorac Surg. 2019; 108: 524-530Abstract Full Text Full Text PDF Scopus (1) Google Scholar In contrast to durable devices, patients who present with acute decompensated heart failure do not always have the luxury of time to determine their transplant candidacy, social supports, or important comorbidities. Usually, the clinical history is brief and pertains to the events leading up to the acute presentation (acute infarct, pulmonary embolus, viral prodrome, etc). Thus, clinicians are faced with assessing the prognosis of the patient in front of them. Common questions include the following: Has there been a significant period of low cardiac output? How long were resuscitative efforts in place before return of spontaneous circulation (ROSC)? Most experts agree that failure to achieve ROSC within 30 minutes is a poor prognostic indicator of survival.5Singal R.K. Singal D. Bednarczyk J. Lamarche Y. Singh G. Rao V. et al.Current and future status of extracorporeal cardiopulmonary resuscitation for in-hospital cardiac arrest.Can J Cardiol. 2017; 33: 51-60Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar In addition, assessments of end-organ function are critical. While renal failure is common, it is helpful to distinguish acute kidney injury from an acute-on-chronic process. In patients with known chronic kidney disease who are not dialysis dependent, acute cardiogenic shock usually results in a permanent loss of renal function. Hepatic function is also critical to assess and while severe elevations in transaminase levels are frequently reversible, the onset of auto-anticoagulation with elevations in international normalized ratio is a poor prognostic marker. Likewise, the concept of metabolic shock compounding circulatory shock is gaining favor as a prognostic indicator. Patients who are profoundly acidotic (pH< 7.0) or with high lactate levels (>15 mmol/L) have poor prognosis and likely should not be offered support. When medical history is available, the presence of comorbid conditions will influence our decision to offer mechanical support. Patients with pre-existing neurologic deficits or those with a known degenerative neurologic disorder are poor candidates for MCS. Similarly, patients with previous vascular surgical interventions and/or known carotid or aorto-iliac disease are at high risk for complications during MCS. Patients with known metastatic malignancies should not be offered support. Other chronic disease states such as end-stage pulmonary disease or heart failure may also preclude support. In the case of known heart failure, we will offer short-term support as a bridge to decision in a patient who is potentially a transplant candidate. However, in a patient previously declined for transplant, we will not offer emergency short-term support as a bridge to destination therapy-ventricular assist device. Table 1 illustrates the common predictors of poor outcome in patients being considered for short-term MCS.Table 1Predictors of poor outcome following short-term mechanical circulatory supportPredictorCommentsAdvanced ageVariable based upon institutional guidelines. Generally, survival falls after age 60 y.Prolonged resuscitationInfluenced by quality of resuscitation (ie, monitored blood pressure, external compression device). Failure to achieve spontaneous circulation within 30 min predicts poor outcome.Renal failureAcute kidney injury is common; however, underlying chronic kidney disease is worrisome.Metabolic shockAbsolute cut-offs may vary by institution. The following are considered contraindications to initiating support at our institution: pH <7.0, bicarbonate <15, lactate >15 mmol/L, INR >5 in the absence of anticoagulation.Neurologic deficitPre-existing neurologic deficit or degenerative neurologic disorder.Peripheral vascular diseasePrevious surgical intervention or known history of carotid or aortoiliac disease.Comorbid diseaseKnown malignant disease with poor prognosis. Chronic obstructive pulmonary disease. Pre-existing heart failure in a nontransplant candidate.INR, International normalized ratio. Open table in a new tab INR, International normalized ratio. An acute septic process is also associated with poor prognosis and while this remains a controversial topic, extracorporeal life support (ECLS) for primary sepsis, in the absence of a reversible cause, is associated with poor outcome. Veno-venous extracorporeal membrane oxygenation (ECMO) is commonly offered for acute respiratory failure due to overwhelming pneumonia, but this is primarily to provide oxygenation and not circulatory support. Patients with sepsis usually have a high cardiac output, so the development of cardiac dysfunction likely predicts an irrecoverable situation. Postcardiotomy shock remains a common indication for ECLS. Table 2 is a summary of the 2016 ELSO (Extracorporeal Life Support Organization) registry report.3Thiagarajan R.R. Barbaro R.P. Rycus P.T. Mcmullan D.M. Conrad S.A. Fortenberry J.D. et al.Extracorporeal life support organizing registry international report 2016.ASAIO J. 2017; 63: 60-67Crossref PubMed Scopus (350) Google Scholar In this report, acute fulminant myocarditis portends the best survival (65%). While the adult cardiogenic shock population is not otherwise specified, the vast majority of these patients represent either acute ischemic shock or postcardiotomy shock. In our own unpublished observations, we see very poor survival in these subgroups, particularly if the patient is older than 60 years. While it is often difficult to decline therapy for an otherwise-healthy-appearing 65-year-old patient with acute cardiogenic shock secondary to an infarct, one must recognize that advanced age is associated with comorbidities such as renal dysfunction, diabetes, and peripheral vascular disease, all of which may have been unrecognized before presentation.Table 2Indications and survival for adult cardiac extracorporeal life supportModified from the 2016 Extracorporeal Life Support Organization Registry.IndicationNumber of patientsMean support time, hSurvivalShock208314442%Myocarditis22718865%Cardiomyopathy70416251%Congenital42012937% Open table in a new tab An important observation is that the average duration of support for cardiac ECLS is approximately 5 to 7 days, which is in stark contrast to respiratory (particularly veno-venous) ECLS, which commonly provides therapy for weeks. This is likely due to the fact that cardiac ECLS is usually used as a bridge to decision. In our experience, 48 to 72 hours of support is usually sufficient to establish adequate end-organ perfusion to assess reversibility of organ failure and importantly, to assess neurologic status. While native myocardial recovery may not be evident at 48 hours, one usually has had an opportunity to assess candidacy for transplant or long-term mechanical support. Therefore, by 7 days, a decision has been made to withdraw support, explant for recovery, or upgrade to a durable device as either a bridge to transplant or long-term therapy. Depending upon jurisdiction, donor organ availability may favor the prolonged use of ECLS as a direct bridge to transplant. Several predictive models have been developed to help clinicians in their decision-making process with this challenging patient population. Perhaps the most quoted score is the Survival After Veno-Arterial ECMO (SAVE) score.6Schmidt M. Burrell A. Roberts L. Bailey M. Sheldrake J. Rycus P.T. et al.Predicting survival after ECMO for refractory cardiogenic shock: the survival after veno-arterial ecmo score.Eur Heart J. 2015; 36: 2246-2256Crossref PubMed Scopus (349) Google Scholar Using 12 pre-ECMO variables, the authors developed 5 risk categories: SAVE score risk categories I (≥5), II (1-5), III (−4 to 0), IV (−9 to −5), and V (≤−10). Mortality increases as the SAVE score drops from category I to V. Similarly, the ENCOURAGE (prEdictioN of Cardiogenic shock OUtcome for Ami patients salvaGed by VA-ECMO) score used 7 pre-ECMO variables to derive a predictive model.7Muller G. Flecher E. Lebreton G. Luyt C.-E. Trouillet J.-L. Bréchot N. et al.The ENCOURAGE mortality risk score and analysis of long-term outcomes after VA-ECMO for acute myocardial infarction with cardiogenic shock.Intensive Care Med. 2016; 42: 370-378Crossref PubMed Scopus (199) Google Scholar Compared with SAVE, this model had better predictive capability, albeit in a homogeneous population of patients suffering refractory cardiogenic shock secondary to acute myocardial infarction. The 5 ENCOURAGE risk categories showed progressively greater mortality out to 30 days. While the focus thus far has been on cardiac ECLS as the primary therapy for acute cardiogenic shock, there are other options available depending on institutional preference and experience.8Tsuneyoshi H. Rao V. The role of extracorporeal membrane oxygenation (ECMO) therapy in acute heart failure.Int Anesthesiol Clin. 2012; 50: 114-122Crossref PubMed Scopus (7) Google Scholar The Impella line of devices (ABIOMED Corp, Danvers, Mass) consist of small axial flow devices that are usually inserted percutaneously via either the femoral or axillary artery. The smaller devices are capable of providing greater than 3 L/min of support and are increasingly being used to support high-risk percutaneous coronary artery interventions. There is a larger Impella 5.0 device that usually requires surgical cut-down to insert and can provide in excess of 5 L/min of flow. Unfortunately, a randomized trial comparing Impella with intra-aortic balloon pump support in acute cardiogenic shock failed to demonstrate any survival benefit, and use of Impella was associated with greater adverse events.9Ouweneel D.M. Erikson E. Sjauw K.D. van Dongen I.M. Hirsch A. Packer E.J.S. et al.Percutaneous mechanical support versus intra-aortic balloon pump in cardiogenic shock after acute myocardial infarction.J Am Coll Cardiol. 2017; 69: 278-287Crossref PubMed Scopus (314) Google Scholar An interesting concept is to use the Impella device to prevent subsequent left ventricular (LV) dysfunction by unloading the acutely ischemic ventricle before revascularization. The door to unloading STEMI (ST Elevation Myocardial Infarction) trial randomized patients to immediate versus delayed (30-minute) Impella support before percutaneous revascularization. This small, 50-patient trial demonstrated that there were no safety or feasibility issues with delayed reperfusion, and there was a nonsignificant trend to a reduction in infarct size (15% to 13%).10Kapur N.K. Alkhouli M.A. DeMartini T.J. Faraz H. George Z.H. Goodwin M.J. et al.Unloading the left ventricle before reperfusion in patients with anterior ST-segment elevation myocardial infarction.Circulation. 2019; 139: 337-346Crossref PubMed Scopus (89) Google Scholar A larger pivotal trial to determine the efficacy of such a strategy has been recommended. We have employed the Impella device in selected clinical situations for the treatment of acute cardiogenic shock. Patients must have adequate right ventricular (RV) function, no evidence of pulmonary edema, and no evidence of apical thrombus. In addition, they need adequate femoral access for either percutaneous or surgical insertion. Once in place, the Impella can act as an effective LV decompression device should ECLS subsequently be required. Several centers routinely employ the Impella after the initiation of ECLS; however, in our experience, this is cost-prohibitive and associated with a greater incidence of limb ischemia, hemolysis, and aortic insufficiency. Our preferred venting strategy is a percutaneous left atrial vent inserted via the femoral vein.11Alhussein M. Osten M. Horlick E. Ross H.J. Fan E. Rao V. et al.Percutaneous left atrial decompression in adults with refractory cardiogenic shock supported with veno-arterial extracorporeal membrane oxygenation.J Card Surg. 2017; 32: 396-401Crossref PubMed Scopus (21) Google Scholar For patients with an open chest suffering from postcardiotomy shock, we prefer to use central cannulation supported by a CentriMag device (Abbot Laboratories, Abbot Park, Ill). This device allows for isolated left, right, or biventricular assistance and can be connected to an oxygenator to provide full cardiopulmonary support. There are other percutaneous mechanical support devices in development. The TandemHeart (LivaNova; Pittsburgh, Pa) is approved by the Food and Drug Administration and uses a trans-septal cannula to provide left-sided support and has a unique dual lumen catheter (Protect-Duo) to provide isolated RV support. Again, this device can be connected to an oxygenator to provide full cardiopulmonary support if required. The decision to use percutaneous or central cannulation is dependent on a lot of patient-specific factors, including body habitus, the mode of presentation (de novo vs postcardiotomy), and the presence of antiplatelet agents that may complicate sternotomy or thoracotomy. A unique approach to provide acute support has been proposed by the Columbia group.12Takeda K. Garan A.R. Ando M. Han J. Topkara V.K. Kurlansky P. et al.Minimally invasive CentriMag ventricular assist device support integrated with extracorporeal membrane oxygenation in cardiogenic shock patients: a comparison with conventional CentriMag biventricular support configuration.Eur J Cardiothorac Surg. 2017; 52: 1055-1061Crossref PubMed Scopus (21) Google Scholar The authors employ standard peripheral cannulation for ECLS consisting of femoral venous to axillary artery flow. A small left thoracotomy incision is made to facilitate the insertion of an LV apical vent which is then connected to the venous inflow line. An oxygenator (if needed) can be spliced into the femoral venous circuit and removed if pulmonary function recovers. If RV function also recovers, the femoral venous line is removed rendering the patient dependent on isolated LV support. This may be a useful strategy as a bridge to transplant, but in the event a durable device is required, the LV apical cannulation site can be employed for LVAD inflow. Figure 1 illustrates our institutional algorithm for consideration of short-term mechanical support and the decision tree for device selection. To further illustrate the issues surrounding the decision to provide short-term MCS, we will frame the decision-making process around a clinical case. A 55-year-old male patient with no previous cardiac history presented to an outside hospital with evidence of an acute anterior ST elevation myocardial infarction complicated by cardiogenic shock. Successful percutaneous coronary intervention was performed to the culprit left anterior descending artery lesion, but there was residual 3-vessel coronary artery disease. Percutaneous coronary intervention was complicated by recurrent ventricular tachycardia with hemodynamic compromise. We were consulted and advised the local center to proceed with peripheral ECLS. They decided to stabilize the patient with an intra-aortic balloon pump and an intravenous lidocaine and amiodarone infusion. Overnight, the patient displayed progressive oliguria and increasing pressor requirements. The following morning, we were re-consulted and agreed to accept the patient in transfer for consideration of advanced heart failure therapies. On admission to our unit, the patient was not intubated and supported with oxygen at 4 L/min by nasal prongs. He had evidence of shock liver with transaminases 2 to 3 times above normal but a normal bilirubin and preserved coagulation. He was oliguric but not anuric and responded to a diuretic challenge. His creatinine was elevated at 200 μmol/L and appeared to have plateaued. He was hemodynamically stable on dobutamine and norepinephrine. He received ticagrelor 24 hours before admission, and thus the decision was made to manage him conservatively with a plan to offer peripheral ECLS if he deteriorated. In the following 48 hours, a rudimentary transplant screen was performed, and no obvious contraindications to cardiac transplantation were present. The patient had excellent social supports and both the family and the patient consented to advanced therapies, realizing that long-term MCS was a possible outcome. He underwent surgical revascularization supported by cardiopulmonary bypass and weaned with the aid of a CentriMag LV assist device. He was extubated the following morning and displayed recovery of LV function by postoperative day 3. After aggressive diuresis, he was returned to the operating room on postoperative day 5 for decannulation of the LV assist device. His subsequent postoperative course was uneventful, and he was discharged on postoperative day 9. Reviewing the preceding course of there are decision that may have in therapy. if ventricular tachycardia into ventricular and ROSC was not within 30 we have advised ECLS if he such that on transfer he had evidence of end-organ injury bilirubin and international normalized ratio and/or metabolic >15 μmol/L or pH we not have offered MCS. if he displayed a progressive after presentation but had and/or sepsis, we that the of recovery was poor and not offer support. transplant if we that he had evidence of underlying chronic kidney disease and presented with anuric renal failure, it be that we have offered him advanced therapies. if the family and/or patient was to accept the of long-term mechanical support and thus the for of in the event of LV function, we not proceed to there are risk that can be employed to determine of short-term MCS can a outcome or if it is a it is an decision to decline support in a patient with a very and often the patient is the opportunity to from MCS. A decision process can be employed to determine of support is failure to demonstrate neurologic recovery is an indication to withdraw support. these patients may present as organ particularly if renal and respiratory function has V. J. E. A. et of organ after circulatory of on of organ from with neurologic of 2017; PubMed Scopus Google Scholar Once circulatory support has been a medical and can be An transplant with consideration of candidacy for durable mechanical support should be of progressive end-organ failure, onset of sepsis refractory to pressor support and of an strategy (ie, transplant or durable ventricular assist should consideration of after 5 to 7 of support. clinicians with acute cardiogenic shock, it is a to offer MCS as a bridge to decision. this results in the need to withdraw support in a patient who is either septic or failure adequate circulatory support. When such an outcome is it to offer circulatory support. 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